Re: [bess] A question about the draft-wang-bess-sbfd-discriminator

["Wanghaibo (Rainsword)" <[e-mail]>]

Hi Reshad,

       Thanks for your comments first.

|Authors, in section 3.1 3rd paragraph, last sentence, I'm not sure I fully understand. Instead of |having 2 S-BFD sessions on PE3 (as initiator) to PE1 and PE2 (the responders), how are you merging |this into 1 single session?
[Haibo]: There may be a misinterpretation of the description here. Here we want to say, for PE3 (as initiator) and PE1 (as the responder)，there may be some SBFD sessions used to detect the VPNSID. For this case, we may merged them to an SBFD session used to detect the PE3’s locator.


|Also, I think the document would be clearer if the terms initiator and responder (as per RFC7880) are |used in the document.
       [Haibo]: We will modified it in the next version.


Regards,
Haibo

From: Reshad Rahman [mailto:[e-mail]]
Sent: Tuesday, March 15, 2022 10:36 AM
To: Wanghaibo (Rainsword) <[e-mail]>; [e-mail]; BESS <[e-mail]>; rtg-bfd WG <[e-mail]>; Greg Mirsky <[e-mail]>
Subject: Re: A question about the draft-wang-bess-sbfd-discriminator

Hi Greg, authors,


Greg, is your point is that instead of having a pair of S-BFD sessions between 2 PEs, we can have 1 (traditional) BFD session between 2 PEs? In general I agree that S-BFD is better suited when only 1 side needs to perform continuity tests.

Authors, in section 3.1 3rd paragraph, last sentence, I'm not sure I fully understand. Instead of having 2 S-BFD sessions on PE3 (as initiator) to PE1 and PE2 (the responders), how are you merging this into 1 single session?

Also, I think the document would be clearer if the terms initiator and responder (as per RFC7880) are used in the document.

Regards,
Reshad.


On Monday, March 14, 2022, 12:44:55 PM EDT, Greg Mirsky <[e-mail]<mailto:[e-mail]>> wrote:


Hi Haibo and the Authors,
thank you for updating the draft. I've read the new version and have a question about the use case presented in the document. There are three PEs with two of them providing redundant access to a CE. It appears that a more general case would be if both CEs use redundant connections to the EVPN. Asume, PE4 is added and connected to CE2. In that case, it seems reasonable that each PE is monitoring remote PEs, i.e., PE1 monitors PE3 and PE4, PE2 - PE3 and PE4, PE3 - PE1 and PE2, and PE4 - PE1 and PE2. So, now there are pairs of S-BFD sessions between PEs connected to CE1 and CE2 respectively. That seems like too many sessions and that number can be reduced if one uses BFD instead of S-BFD. Would you agree? To simplify operations, it might be helpful to use the technique described in draft-ietf-bfd-unsolicited<https://datatracker.ietf.org/doc/html/draft-ietf-bfd-unsolicited-09>. In the recent discussion of the draft on the BFD WG ML, the authors noted that they are working on extending the scope to include the multi-hop BFD.
Greatly appreciate your thoughts about the number of S-BFD sessions.

Regards,
Greg